The present invention relates to a magneto-optic sensor for use in electrical measuring systems. More particularly, the invention relates to a Faraday effect sensor where electrical field intensity is measured by the rotation of a polarized light beam passing through a transparent magnetically active medium. The present invention is well suited for coupling to a fiber optic light cable.
Present sensors of this type typically employ a pair of collimators and a pair of polarizers which define a light conduction path through the transparent magnetically active material. A magnetic field to be measured is produced near the sensor. Often the field is produced by a current to be measured flowing through a conductor. Light radiation traversing this path experiences an intensity variation which is proportional to the instantaneous amplitude (positive or negative) of the current. Therefore, by comparing the intensities of the light radiation at the input and output of the light conduction path, it is possible to obtain a current measurement.
Typically the light radiation is generated by a light emitting element and received by a photo detector, each of which is coupled to one end of the light conducting path of the sensor by a respective fiber optic cable. The light emitting element and the photo detector are electrically connected to form part of a suitable processing circuit.
While such a system is generally capable of providing a good current measurement, it is frequently desired to employ a more compact sensor for use with a high permeability core as a passive current sensor. In such a situation, the size of the sensor is of great importance.